Vania



1. C. KOPF.

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LIFTING JACK.

APPLlcAnoN msn MMI. 22. Isls.

Y -Patentd Nov. 1l, 1919.

2 SHEETS-SHEET 2.

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UNITED STATES PATENT OFFICE.

JOHN C. KOPF, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO THE DUFF MANUFAC-TUBING' COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYL-VAN IA.

LIFTING-JACK.

To all 'whom z't ma concer/n:

Be it known t at I, JOHN C. Korr of Pittsburgh, Allegheny county, Pennsyvania, have invented a new and useful Imrovement in Lifting-Jacks, ofwhich the ollowing is a full, clear, and exact description, referencebeing had to the accompanying drawings, forming part of thisspecification, in which- F1 re 1 is a developed vertical section of alifting jack embodying my mventlon, the general plane of the sectionbeing on the line I-'-I of Fig. 2;

nig 2 is a horizontal section on the irre ar line II-II of Fig. 1;

ig. 3 is a perspective View of the clutchbarrel and its brake band;

Fig. 4 is a detail sectional view showin one of the friction clutchdisks and its enga ement with its shaft; and

ig. 5 is a plan view showing one of the co erating friction clutchdisks. v

y invention has relation to lifting Jacks and more articularly to screwjacks.

One of tlie ob'ects of m invention is to provide a jack o this typeaving means of simple, novel and effective character, whereby the actionof the load on the jack 1s caused to automatically lock the jack againstlowering movement while the load is being held or lifted. A furtherobject is to provide locking means ofa` this character in which thelockin action is directlyfproportional to the loa on the jack, Vso thatsuch action increases as the load increases.

A still further object is to provide novel and effective means inconnection with the locking means, whereby the jack may be ra idlyraised and lowered, when desired.

s'xihe nature of my invention will be best understood by reference tothe accompanying drawings in which I have shown the preferred embodimentthereof Aand which will now be described, it being premised, however,that various changes can be made in the details of construction andgeneral arrangement of the parts, without d eparting from the spirit andscope of my invention as defined in the appended claims.

In these drawings, the numeral 2 designates the base of the jack havingan upwardly projecting cylindrical column 3, 1n

Specification of Letters Patent.

sprin Patented Nov. `11, 1919.

Application led Harel; 22, 1919. Serial No. 284,318.

which is secured the internally threaded nut 4. 5 designates the screwof the jack, which extends through the nut 4 and downwardly in thecolumn 3. Surrounding the column 3 is a lifting shell 6, having securedtoits upper end the casing 7, in whichthe operating parts resently to bedescribed are mounted, and w ich carries at its upper end a liftingplate 8 to receive the load. This late is provided with ball bearingsat9.

xtendm through a suitable bearing 10 in the si e of the casing is anactuatin stub shaft 11, adapted to receive the usua operating lever (notshown). At its inner end, said 4shaft carries the beveled pinion 12,whose teeth mesh with the horlz'ontal beveled gear 13, which is keyed tothe upper portion of the screw 5.

As thus far described, the parts are, in general, of well knowncharacter and form no part of my present invention except incombination. 14 desi ates a clutch' member havinga saw-toot ed clutchface on its lower side and which is keyed to the screw 5 to rotatetherewith and to move vertically thereon. This clutch member is pressedby 15 into engagement with the corres on ln'gly forme clutch face of a.second c utch member 16, which is loosely mounted on the screw 5, justabove the thread thereof. The clutch member 16 is formed on itsperiphery with worm teeth 17, which engage the threads of a worm 18,secured to a horizontal shaft 19 mounted in vsuitable bearings in thecasing 7. This shaft 19 is extended through the casing at one end and isvided with ahand crank 20. This shaft 19 is also provided with amultiple disk friction clutc device comprising one set of clutch disks21, which are engaged with the shaft 19 to rotate therewith, and anotherset of intercalating disks 22, which are eng ed on their peripherieswith a barrel 23. his barrel has a cylindrical outer surface which issurrounded by a friction brake band 24, one end of this band beingconnected to a fixed pin 25, and the other end to a rod 26, whose end isconnected to a lever 27, having a cam or eccentric portion 28, whichbears against the casing 7. A spring 29 is arranged to act on the rod26.

The threads on the screw 5 and also the threads on the worm 18, are ofrelatively quick pitch, so that said screws will readily rotate underthe action of a load on the jack. The operation is as follows:

The screw and the liftin head or plate 8 can be quickly run up to t eload by turning the crank 20 and thereby turning the screw through theaction of the worm 18 and worm wheel 16, the clutch faces of the members14 and 16 engaging to cause Said members to rotate together and therebyturnthe screw. The shaft 11 is then actuated by its lever in the usualmanner to further raise the screw and lift the load. During theload-lifting operation, it will be readily seen that the clutch member14 will turn with reference to the clutch member 16, and said memberswill act as a safety .device to prevent the load running down.

The ciutch member 16 is prevented from turning during this actionbecause of the fact that it is engaged with the worm 18, and the actionof the load causes an end thrust on the worm shaft 19, which forces thedisks of the friction clutch into frictional engagement. The extent ofthe frictional action of this clutch is directly proportional to theload on the screw increasing as the load increases.

When it is desired to lower the load, the lever27 is turned from theosition shown in Fig. 1 to a position in w lich the lower portion of itscam lor eccentric bears on the casing. This permits an endwise movementof the rod 26 and releases the brake band 24. The barrel 23 is now freeto turn, and the entire friction clutch device including said barrel nowturns with the shaft 19. This releases theresistance acting on theclutch member 16, and the lowering action can then becontrolled bymanipulation of the lever 27. Also, the friction clutch device may beleft inand the lowering controlled by the crank 20. In this manner, thejacks can be lowered to any desired extent and stopped in the desiredposition.

The advantages of my invention will be apparent to those familiar withjacks of this type, since it rovides a high-speed jack capable of hanlino' large loads with perfect safety, the lodking action againstaccidental lowering of the load increasing as the load increases. At thesame time, the invention provides means whereb the load may be quicklylowered to any esired extent whenever necessary.

The method of construction and Inode of operation is simple, and thepartsA thereof are strong and of durable character.

I claim:

l. A liftin jack having a lifting screw, two indepen ent sets ofmechanisms connected to the screw whereby it may be raised and lowered,one of said sets of mechanisms including an automatic clutch to preventthe screw from rotating in one direction and to permit free rotation ofthe screw in the other direction by the other mechanism, said clutchbeing mounted on the shaft of the screw, and another clutch device forcontrolling the operation of the first named clutch, substantially' asdescribed.

2. A lifting jack having a lifting screw, means for actuating said screwto raise the load, a two-part clutch, one member of which is mounted torotate with the screw and the other member of which is loosel f mountedwith respect to the screw, a quick pitch worm geared to the first namedclutch member and having an endwise movable shaft, manually operatedactuating means for said shaft, a brake device ap lied to said shaft,and manually operatec means for controlling said brake device;substantially as described.

3. A lifting jack comprising a lifting screw, means for actuating saidscrew to raise the load, a clutch device having one member fixed torotate with the screw and another member mounted loosely with respect tothe screw, said last named member having worm teeth thereon, a wormshaft, a worm on said shaft engaging said teeth, means for manuallyoperating said shaft, and a friction brake device comprising frictionelements carried by said shaft, and other coperating friction elementscarried independently of the shaft, and manually controlled means foreffecting the engagement and disengagement lof the two sets of frictionbraking elements; substantially as described.

4. A lifting jack having a lifting screw, means for actuating said screwto raise the load, a clutch havin one member mounted for rotation with te screw and another member loosely mounted with respect to the screw,the last named member having worm teeth on its periphery, a worm shaft,a crank for actuating said shaft, Va worm on said shaft and engagingsaid worm teeth, a barrel or,casing surrounding said shaft, a set offriction members carried by the barrel or casing, a coperatin set offriction members carried by sai shaft, and means whereby the barrel orcasing may be held against movement or mav be free to turn with the wormshaft, substantially as described.

5. A lifting jack having a lifting screw, means for actuating said screwto raise the load, a clutch having one mem'ber mounted for rotation withthe screw and another member loosely mounted with respect to the screw.the last named member having worm teeth on its periphery, a worm shaft,a crank for actuating said shaft, a worm on said shaft and engaging saidworm teeth,

barrel or casing surrounding said shaft, ing a brake band engaging thebarrel or a set of friction members carried by the casing and a handledevice vfor. applying barrel or cnsin another set of frlcton andreleasing the brake band,substa.nt1ally 10 members carrie by the shaft,and means as described.

whereby the barrel or casing may be held In testimony whereof, I havehereunto against movement or may be freed to turn set my hand.

with the Worm shaft, sand means `compris- JOHN C. KOPF.

